The present invention relates generally to the administration of drugs, and more particularly to the dissolution and admininistration of drugs from dry formulations.
Injection of micro-quantities of soluble drug is used extensively throughout the world for a wide range of drugs, reagents and biological substances. Many of these reagents are unstable in their liquid form under various conditions. An effective method for maintaining these unstable drugs in a stable condition is to keep the reagent as a dry formulation.
Current methods for administering dry formulations into patients involves adding a liquid diluent into a vial containing the dry reagent to be administered. The dry reagent is allowed to dissolve within the vial. This frequently requires some minimal agitation. Too much agitation can result in foaming of the reagent and preventing recovery of the appropriate amount of drug to administer to the patient. Following dissolution of the reagent, the reagent solution is withdrawn from the vial in a syringe. This charged syringe is then used to inject the patient. To assure that the proper amount of reagent is delivered, it is desirable to be able to view the reagent as it is administered.
One type of device for administering liquid drugs to a patient is the single-use syringe design described in U.S. Pat. No. 5,222,948. This device provides a means of a single use injection with a one way valve system that incorporates a needle and a separate solution chamber. The reagent to be delivered is contained as a solution within the solution chamber. For many applications, the reagent should remain stable in solution over relatively long periods of storage and/or transportation. Unfortunately, many reagents that could be delivered from this device are not stable in solution. Such reagents are, as a rule, considerably more stable as a dry form, i.e., powder or lyophilized.
The description herein describes systems, devices and methods for providing fluid forms of bioactive reagent from dry forms of the reagent.
In accordance with one aspect of the invention, a system is provided for delivering single dose units of medical reagents in fluid form. The system includes a chamber that houses a dry reagent bed having a mass of no more than about 1.0 g. A compression component in the chamber exerts pressure upon the reagent bed. A delivery mechanism is integrally connected downstream of the chamber for delivering the reagent in a liquid.
In the illustrated embodiments, the system also includes an upstream source of diluent for reconstituting the dry reagent in fluid form within the chamber, in route to the delivery mechanism. The preferred delivery mechanism is an injection needle.
In accordance with another aspect of the invention, a method is provided for preparing and delivering a defined drug dose. The method includes converting a dry reagent into a fluid form by flowing a diluent along a laminar flow path through a chamber that houses the dry reagent. The fluid is then delivered from the chamber directly into a delivery mechanism in fluid communication with a drug recipient.